RT.com wrote:Around 950 people have sought medical attention in Chelyabinsk alone because of the disaster, the region's governor Mikhail Yurevich told RIA Novosti. Over 110 of them have been hospitalized and two of them are in heavy condition. Among the injured there are 159 children, Emergency ministry reported.Army units found three meteorite debris impact sites, two of which are in an area near Chebarkul Lake, west of Chelyabinsk. The third site was found some 80 kilometers further to the northwest, near the town of Zlatoust. One of the fragments that struck near Chebarkul left a crater six meters in diameter.

Found the movie to which I referred. Turned out to be "Alien Trespass" from 2009; it's the story that takes place in 1957 Mohave Desert. We didn't get past the first ten minutes. http://www.imdb.com/title/tt1122836/

How much distruction would this asteroid cause if it struck Antarctica? Heat melting Ice and Snow, fracturing Ice Shelves, and causing a large influx of fresh water into the southern oceans. Anyone care to estimate the size of the tsunami's

BMAONE23 wrote:How much distruction would this asteroid cause if it struck Antarctica? Heat melting Ice and Snow, fracturing Ice Shelves, and causing a large influx of fresh water into the southern oceans. Anyone care to estimate the size of the tsunami's

This object wasn't large enough to reach the ground carrying cosmic velocity. So it wouldn't have caused any damage at all. Are you talking about DA14? Likewise, not large enough to do more than create a crater a few hundred feet across at most, and not enough energy to produce a tsunami.

NASA experts will hold a teleconference for news media at 4 p.m. EST today to discuss a meteor that streaked through the skies over Russia's Urals region this morning.

Scientists have determined the Russia meteor is not related to asteroid 2012 DA14 that will safely pass Earth today at a distance of more than 17,000 miles. Early assessments of the Russia meteor indicate it was about one-third the size of 2012 DA14 and traveling in a different direction.

Panelists for the teleconference are:-- Bill Cooke, lead for the Meteoroid Environments Office at NASA's Marshall Space Flight Center in Huntsville, Ala.-- Paul Chodas, research scientist in the Near Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

News media interested in participating should dial 888-843-7186 and use the passcode METEOR.

BMAONE23 wrote:How much distruction would this asteroid cause if it struck Antarctica? Heat melting Ice and Snow, fracturing Ice Shelves, and causing a large influx of fresh water into the southern oceans.

Good Lord! It is like a bombardment! What could cause that amount of such prolonged and repeated noise? Chris wrote something earlier on about this - but I could really appreciate detailed explanation, please, if possible.

Margarita

"In those rare moments of total quiet with a dark sky, I again feel the awe that struck me as a child. The feeling is utterly overwhelming as my mind races out across the stars. I feel peaceful and serene."

MargaritaMc wrote:Good Lord! It is like a bombardment! What could cause that amount of such prolonged and repeated noise? Chris wrote something earlier on about this - but I could really appreciate detailed explanation, please, if possible.

When a large body breaks up below about 30 miles, it generates an overpressure event. A shock wave. Basically, what we have here is a fairly low altitude explosion that over just a couple of seconds released the equivalent energy of many tons of TNT. That's going to move a lot of air.

"In those rare moments of total quiet with a dark sky, I again feel the awe that struck me as a child. The feeling is utterly overwhelming as my mind races out across the stars. I feel peaceful and serene."

My Russian is now minimal, but the label of the second of the two YouTube videos posted above by tawilson translates as"Chelyabinsk 15.02.13 From the Ural (came?) Meteorite 2012DA14"So one person at least thought it was DA14.

M

"In those rare moments of total quiet with a dark sky, I again feel the awe that struck me as a child. The feeling is utterly overwhelming as my mind races out across the stars. I feel peaceful and serene."

"In those rare moments of total quiet with a dark sky, I again feel the awe that struck me as a child. The feeling is utterly overwhelming as my mind races out across the stars. I feel peaceful and serene."

A meteoroid is a sand- to boulder-sized particle of debris in the Solar System. The visible streak of light from a meteoroid, heated as it enters a planet's atmosphere, and the glowing particles that it sheds in its wake is called a meteor, or colloquially a "shooting star" or "falling star". Many meteors appearing seconds or minutes apart, and appearing to originate from the same fixed point in the sky, are called a meteor shower. The root word meteor comes from the Greek meteōros, meaning "suspended in the air". If a meteoroid reaches the ground and survives impact, then it is called a meteorite.

Asteroids are small Solar System bodies that are not comets. The term asteroids historically referred to objects inside the orbit of Jupiter. They have also been called planetoids, especially the larger ones. These terms have historically been applied to any astronomical object orbiting the Sun that did not show the disk of a planet and was not observed to have the characteristics of an active comet, but as small objects in the outer Solar System were discovered, their volatile-based surfaces were found to more closely resemble comets, and so were often distinguished from traditional asteroids.[1] Thus the term asteroid has come increasingly to refer specifically to the small bodies of the inner Solar System within the orbit of Jupiter, which are usually rocky or metallic. They are grouped with the outer bodies—centaurs, Neptune trojans, and trans-Neptunian objects—as minor planets, which is the term preferred in astronomical circles.[2] This article uses the term "asteroid" to the minor planets of the inner Solar System.

A comet is an icy small Solar System body (SSSB) that, when close enough to the Sun, displays a visible coma (a thin, fuzzy, temporary atmosphere) and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles.

Chris Peterson wrote:There will probably be connections made to asteroid DA14, making its very close pass by the Earth now. However, it is completely certain that the two events are unrelated. With all the witnesses and video, it will be easy to reconstruct the orbit of this object, and I expect to see the first estimates very quickly. I expect there will be a number of papers at the Meteoroids 2013 conference this summer!

Besides the 12+ hour time difference this seems to be coming in from the east (i.e., sunrise) whereas DA14 will be coming from the south.

It is still possible that the two separate asteroids conspired like a pair of velociraptors:

DA14 distracted everyone's attention whilethe Chelyabinsk meteor snuck in with the sun at its back so that it wouldn't be detected.............................................................................

Romeo and Juliet Act 3, Scene 5

JULIET: Yon light is not day-light, I know it, I:

It is some meteor that the sun exhales,

Last edited by neufer on Sat Feb 16, 2013 7:35 pm, edited 1 time in total.

When we see the more distant videos, the meteor is seen to undergo a disruption event, after which the remaining material looks like it burns off. I presume that the videos showing the curious double smoke trail were made underneath the disruption event. The shock wave arrives more than 30 seconds after that event- perhaps 60 seconds or more. That places the height of the event at 10-20 km.

It is nearly certain that material survived to the ground, although I haven't seen credible reports of that yet. There are lots of clearly bogus reports, as well as outright faked or misattributed images.

This fell in Russia, a country with a culture that is deeply engrossed by pseudoscience and has one of the most credulous populations of any developed nation. Big fireballs falling in such places tend to result in some rather extreme reports, so everything here needs to be viewed with a healthy degree of skepticism. I expect the number of actual injuries is smaller, and mainly caused by glass that shattered when the shock wave hit. If past events are any indication, there will also be many reports that simply reflect hysteria.

While some parallels have been drawn to the Tunguska event, the more interesting comparison is with the Sikhote-Alin fall of 1947. It occurred on February 12, which is very close to the February 15 date of this event. At about 100 tons, it may have been similar in size to this. Sikhote-Alin was iron, which allowed it to survive very deep in the atmosphere, with the terminal explosion occurring at around 6 km. This low explosion resulted in a remarkable 20% of the original mass surviving- some reaching the ground without losing all its cosmic velocity, producing some small craters. Almost all meteoroids are stony, not iron, and the atmospheric trails of large fireballs are usually very smoky. For the size of this event, the trail seems very thin to me. For that reason, I would not be surprised if it was an iron. It clearly exploded much higher than Sikhote-Alin, so more of it will have burned up.

There will probably be connections made to asteroid DA14, making its very close pass by the Earth now. However, it is completely certain that the two events are unrelated.

With all the witnesses and video, it will be easy to reconstruct the orbit of this object, and I expect to see the first estimates very quickly. I expect there will be a number of papers at the Meteoroids 2013 conference this summer!

10 to 20 km altitude explosion did that level of damage. How many time stronger would the chockwave be if the explosion happen at 4 or 5 km altitude ( Denser atmosphere)? Look to me they were very very lucky in their badluck overthere.

But there are a lot of minor errors. It would be more correct to say that the bright fireball was created by heating the air in front of it. The object didn't enter the atmosphere at a height of 32 miles, and the shock that hit the ground isn't properly characterized as a sonic boom, but as an overpressure or shock wave from an explosion. I think that any stories of meteorites hitting anything remain anecdotal. While we expect an event like this to produce meteorites, AFAIK none have been found yet, and no damage can be attributed to them. Even the widely reported hole in the lake can't be positively attributed to this event.

Ann wrote:It is interesting that it happened in Russia, not too far (or so I believe) from where the 1908 Tunguska event took place.

http://en.wikipedia.org/wiki/Tunguska_event wrote:<<The Tunguska event was an enormously powerful explosion that occurred near (and later struck) the Podkamennaya Tunguska River in what is now Krasnoyarsk Krai, Russia, at about 07:14 KRAT (00:14 UT) on June 30 [O.S. June 17], 1908. The explosion, having the epicentre (60.886°N, 101.894°E), is believed to have been caused by the air burst of a large meteoroid or comet fragment at an altitude of 5–10 kilometres above the Earth's surface. Different studies have yielded widely varying estimates of the object's size, on the order of 100 metres.

Although the meteoroid or comet appears to have burst in the air rather than hitting the surface, this event still is referred to as an impact. Estimates of the energy of the blast range from 5 to as high as 30 megatons of TNT—roughly equal to the United States' Castle Bravo thermonuclear bomb tested on March 1, 1954.

The Tunguska explosion knocked down an estimated 80 million trees over an area covering 2,150 square kilometres (i.e. circular area of 52km in diameter). It is estimated that the shock wave from the blast would have measured 5.0 on the Richter scale. An explosion of this magnitude is capable of destroying a large metropolitan area.>>

Correction: this post initially contained a typo that listed the mass of the meteor at 8 tons, we meant 8000 tons. Currently, the estimated mass ranges from 7000 to 8000 tons. -ed

<<What we know (subject to change as more information comes in): At 9:20 a.m. local time in Russia, videos show an impactor coming in from the North. Asteroid 2012 DA14 is approaching Earth from the South. These two events are not related. The body is estimated to have been 15 meters across and weighed roughly 8 tons 8000 tons. The resulting airburst would have the equivalent yield of a 1-10 megaton 500 kiloton explosion. Note that these are very rough and extremely preliminary estimates.>>

Doum wrote:10 to 20 km altitude explosion did that level of damage. How many time stronger would the chockwave be if the explosion happen at 4 or 5 km altitude ( Denser atmosphere)?

It's complicated. The body broke up when it did because the ram pressure forces on it exceeded its material strength. It could not have descended much deeper. If it were made of something stronger (like iron) it could get closer to the ground, but it would also be shedding more energy as it went, making it a smaller, slower body when it finally did explode. So had this exact object penetrated deeper, it would not necessarily have produced more damage. Of course, if it survived low enough, the products of the explosion might hit the ground carrying something of their original velocity, which could be very damaging. That's what happened in the case of the Sikhote-Alin event in 1947- thousands of individual pieces of iron embedded themselves in trees and created dozens of small craters. Over a city, that could be devastating. But the Sikhote-Alin parent body was probably ten times more massive than this one.

Chris Peterson wrote:It would be more correct to say that the bright fireball was created by heating the air in front of it.

It heated the air to ionization; the rapid expansion of which would have created quite a bit of sound.

Chris Peterson wrote: The object didn't enter the atmosphere at a height of 32 miles, and the shock that hit the ground isn't properly characterized as a sonic boom, but as an overpressure or shock wave from an explosion.

Perhaps the visible smoke trail started at a height of 32 miles.

There clearly had to be a strong sonic boom:

http://en.wikipedia.org/wiki/Sonic_boom wrote:<<A sonic boom is the sound associated with the shock waves created by an object traveling through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding much like an explosion. The crack of a supersonic bullet passing overhead is an example of a sonic boom in miniature.>>

No doubt the meteor also broke apart but stories of it loudly exploding remain anecdotal, IMO.

Chris Peterson wrote:I think that any stories of meteorites hitting anything remain anecdotal. While we expect an event like this to produce meteorites, AFAIK none have been found yet, and no damage can be attributed to them. Even the widely reported hole in the lake can't be positively attributed to this event.